A power unit for a hydraulic braking system is described in German Patent Application No. DE 10 2013 200 471 A1. A braking system equipped with the power unit of German Patent Application No. DE 10 2013 200 471 A1 has two brake circuits, each of which is connected via a switching valve to a master brake cylinder and moreover is connected via a pressure relief valve to a brake fluid reservoir. By activating the particular pressure relief valve in such a way that the particular pressure relief valve is at least intermittently present in an at least partially opened state during an actuation of a brake actuating element which is connected to the master brake cylinder, brake fluid is to be displaceable from the associated brake circuit into the brake fluid reservoir to prevent or limit in this way a brake pressure buildup in at least one wheel brake cylinder of the associated brake circuit.